Offshore wind power system fault ride-through control method and system

Abstract

The invention provides an offshore wind power system fault ride-through control method and system, and the method comprises the steps: obtaining the first power of each unit of an offshore wind power plant under a fault ride-through condition and the first adjustment voltage of the AC side of an offshore commutation module through following the fault ride-through condition; adjusting the working mode of each unit of the offshore wind plant according to the first adjustment voltage to obtain the threshold voltage of the unit; obtaining a first reference value of the active power of the units through the fitting operation of the first power and the threshold voltage, and suppressing the rising speed and amplitude of the output voltage of each unit of the offshore wind plant based on the first reference value. The offshore converter module and the land converter module do not need to communicate with the unit, cooperative fault ride-through of the offshore wind turbine unit and the receiving end is realized when the transmission end fails, and the stability of offshore wind power transmission is greatly improved.

Description

Technical Field

[0001] The present application relates to the field of renewable energy power generation technology, and in particular to a fault ride-through control method and system for an offshore wind power system. Background Art

[0002] When the offshore wind farm is transmitted through the flexible DC power exchange station (the flexible DC power exchange station includes the offshore converter module and the land converter module), if the AC power grid at the receiving end is blocked from outputting power due to a fault, during the fault period, the offshore wind farm will continue to inject power into the flexible DC power exchange station, which may cause a power surplus problem. The surplus power must be consumed by additional energy dissipation devices, otherwise it will cause DC overvoltage, which seriously threatens the safe and stable operation of the system. At this time, if the DC side of the land converter module lacks stable voltage support, the offshore converter module may not be able to maintain a constant frequency and voltage at the transmission end, resulting in the offshore wind farm unit towing and the failure of fault crossing.

[0003] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present application and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because they are described in the background technology section of the present application. Summary of the invention

[0004] The embodiments of the present application provide a method and system for controlling fault ride-through of an offshore wind power system.

[0005] The first aspect of the present application provides a fault ride-through control method for an offshore wind power system, which is applicable to an offshore wind power transmission system, wherein the offshore wind power transmission system comprises: at least one unit, an offshore converter module, an electric energy transmission module, a land converter module and a land power grid, wherein the offshore converter module is connected to the unit; the electric energy transmission module is connected to the offshore converter module; the land converter module is connected to the electric energy transmission module; the land power grid is connected to the land converter module; the offshore wind power system fault ride-through control method comprises:

[0006] Based on the fault ride-through condition, obtaining a first power of each unit in the offshore wind farm for the fault ride-through condition and a first adjusted voltage on the AC side of the offshore converter module;

[0007] Based on the first adjustment voltage, adjusting the working mode of each unit in the offshore wind farm to obtain the threshold voltage of the unit;

[0008] Acquire a first reference value of the active power of the unit according to a fitting operation of the first power and the threshold voltage;

[0009] Based on the first reference value, the rising speed and amplitude of the output voltage of each unit in the offshore wind farm are suppressed.

[0010] The second aspect of the present application provides an offshore wind power system fault ride-through control system, which is applicable to an offshore wind power transmission system, wherein the offshore wind power transmission system comprises: at least one unit, an offshore converter module, an electric energy transmission module, a land converter module and a land power grid, wherein the offshore converter module is connected to the unit; the electric energy transmission module is connected to the offshore converter module; the land converter module is connected to the electric energy transmission module; the land power grid is connected to the land converter module; the offshore wind power system fault ride-through control system comprises:

[0011] A first acquisition module, wherein the first acquisition module acquires, based on the fault ride-through condition, a first power of each unit in the offshore wind farm under the fault ride-through condition and a first adjusted voltage on the AC side of the offshore converter module;

[0012] a second acquisition module, wherein the second acquisition module adjusts the working mode of each unit in the offshore wind farm based on the first adjustment voltage to obtain a threshold voltage of the unit;

[0013] a third acquisition module, wherein the third acquisition module acquires a first reference value of the active power of the unit according to a fitting operation of the first power and the threshold voltage;

[0014] A regulating module, wherein the regulating module suppresses a rising speed and amplitude of an output voltage of each unit in the offshore wind farm based on the first reference value.

[0015] The third aspect embodiment of the present application proposes an electronic device, comprising: a processor; a memory for storing instructions executable by the processor; wherein the processor is configured to execute the instructions to implement the offshore wind power system fault ride-through control method proposed in the first aspect embodiment of the present application.

[0016] The fourth aspect embodiment of the present application proposes a non-temporary computer-readable storage medium. When the instructions in the storage medium are executed by the processor of an electronic device, the electronic device can execute the method proposed in the first aspect embodiment of the present application.

[0017] The fifth aspect embodiment of the present application proposes a computer program product, including a computer program, which implements the method proposed in the first aspect embodiment of the present application when executed by a processor in a communication device.

[0018] The technical solution provided by the embodiments of the present application brings at least the following beneficial effects:

[0019] By following the fault ride-through condition, the first power of each unit in the offshore wind farm for the fault ride-through condition and the first adjustment voltage on the AC side of the offshore converter module are obtained; the working mode of each unit in the offshore wind farm is adjusted according to the first adjustment voltage to obtain the threshold voltage of the unit; the first reference value of the unit's active power is obtained by fitting the first power and the threshold voltage, and the rising speed and amplitude of the output voltage of each unit in the offshore wind farm are suppressed based on the first reference value. There is no need for the offshore converter module and the land converter module to communicate with the unit, and the coordinated fault ride-through of the offshore wind turbine and the receiving end is realized when the transmission end fails, which greatly improves the stability of offshore wind power transmission.

[0020] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0022] Figure 1 A schematic flow chart of a fault ride-through control method for an offshore wind power system provided in an embodiment of the present application;

[0023] Figure 2 A schematic diagram of the structure of an offshore wind power transmission system provided in an embodiment of the present application;

[0024] Figure 3 A schematic diagram of a joint fault ride-through process of a flexible DC power station and a generator set provided in an embodiment of the present application;

[0025] Figure 4 A schematic diagram of the structure of a fault ride-through control system for an offshore wind power system provided in an embodiment of the present application;

[0026] Figure 5 A schematic diagram of the structure of an electronic device provided according to an embodiment of the present application;

[0027] Figure 6 It is a schematic diagram of the structure of another electronic device provided according to an embodiment of the present application. DETAILED DESCRIPTION

[0028] Here, exemplary embodiments will be described in detail, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the embodiments of the present application. Instead, they are only examples of devices and methods consistent with some aspects of the embodiments of the present application as detailed in the attached claims.

[0029] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the embodiments of the present application. The singular forms of "a" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0030] It should be understood that, although the terms first, second, third, etc. may be used to describe various information in the embodiments of the present application, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the embodiments of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the words "if" and "if" as used herein may be interpreted as "at..." or "when..." or "in response to determination".

[0031] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0032] It should be noted that the offshore wind power system fault ride-through control method provided in any embodiment of the present application can be executed alone, or can be executed in combination with possible implementation methods in other embodiments, or can be executed in combination with any technical solution in the relevant technology.

[0033] The following describes the offshore wind power system fault ride-through control method and system according to an embodiment of the present application with reference to the accompanying drawings.

[0034] Figure 1 A schematic diagram of a fault ride-through control method for an offshore wind power system provided in an embodiment of the present application is provided. Figure 2 This is a schematic diagram of the structure of an offshore wind power transmission system provided in an embodiment of the present application. Figure 1 As shown, this method is applicable to Figure 2 The offshore wind power transmission system shown includes: at least one unit, an offshore converter module, an electric energy transmission module, a land converter module and a land power grid, wherein the offshore converter module is connected to the unit; the electric energy transmission module is connected to the offshore converter module; the land converter module is connected to the electric energy transmission module; and the land power grid is connected to the land converter module.

[0035] The offshore wind power system fault ride-through control method includes but is not limited to the following steps:

[0036] S101, based on a fault ride-through condition, obtaining a first power of each unit in an offshore wind farm for a fault ride-through condition and a first adjusted voltage on an AC side of an offshore converter module.

[0037] In a feasible implementation, offshore wind farm fault ride-through refers to the ability of wind turbine generator sets to ensure continuous operation without disconnection from the grid and smoothly transition to normal operation state within a certain voltage or frequency range and its duration time interval when the voltage or frequency of the grid connection point (grid connection point refers to the connection point between the land converter module and the land power grid) exceeds the normal operating range allowed by the standard due to power system accidents or disturbances. For fault ride-through, a common idea is to reduce the power generated by the unit or increase the energy sent to the grid side to eliminate the difference between the power generated by the unit and the energy consumed by the grid side. For example, the power generated by the unit can be reduced by reducing the wind energy absorbed by the wind turbine of the unit, but this method has a slow response speed and may not be able to respond to voltage drops in time; the power generated by the generator set can also be reduced by relying on the inertial energy of the unit; it can also be considered to remove the reactive compensation reactance and provide reactive current to the system by investing in a capacitor device connected in parallel at both ends of the line; it can also use the characteristics of the power transmission module itself with a large charging power and a strong capacitance effect to make the power transmission module equivalent to a reactive power source, and provide a certain amount of reactive power when a fault occurs.

[0038] The process of obtaining the first power includes:

[0039] Alternatively, as an example, Figure 2 As shown, the real-time operating status of each unit in the offshore wind farm can be monitored, and the output power P1 of each unit, the equivalent inertia constant of each unit, the rotor speed of each unit and the speed time constant of each unit can be obtained.

[0040] It should be noted that the equivalent inertia constant J, also known as the equivalent moment of inertia, is a measure of the resistance of the unit to change its rotational state when rotating, that is, the rate of change of its angular velocity when the unit is subjected to an external torque. The speed time constant τ, also known as the unit speed control time constant, is a parameter used to describe the time required for the speed / torque of the motor to reach a specific ratio (for example, the ratio can be 63.2%) during the start or stop process, and is used to measure the speed of the wind turbine response to speed changes.

[0041] Optionally, as an example, based on the fault ride-through condition, the equivalent inertia constant J, the rotor speed and the speed time constant τ are fitted to obtain the first adjustment power of each unit. Further, the maximum speed ω of the unit rotor is obtained. MAX and the rotor speed before the fault ω 0; The equivalent inertia constant J, rotor speed and speed time constant τ are fitted through the following relationship to obtain the first adjustment power of each unit:

[0042]

[0043] Optionally, as an example, the output power P1 and the first adjusted power are differentially operated to obtain the first power of each unit in the offshore wind farm for the fault ride-through condition, wherein the first power = output power P1 - first adjusted power. It should be noted that for each unit in the offshore wind farm, based on the output power and the fitting operation, the first power corresponding to each unit for the fault ride-through condition is obtained.

[0044] The process of obtaining the first adjusted voltage on the AC side of the offshore converter module includes:

[0045] Alternatively, as an example, Figure 2 As shown, the first working voltage U1 of the AC side is obtained when the offshore converter module does not have a fault ride-through condition. It should be noted that when the fault ride-through condition does not occur, the unit, the offshore converter module and the land converter module operate stably, and their voltages and voltage amplitudes are stable, and the reference amplitude V1_ref corresponding to the first working voltage U1 is obtained (the reference amplitude V1_ref is the reference amplitude of the AC voltage control of the offshore converter module before the fault).

[0046] Alternatively, as an example, Figure 2 As shown, based on the fault ride-through condition, the first threshold voltage Vth1 of the DC side of the offshore converter module is determined. Further, in response to the fault ride-through condition, the surplus power transmitted to the offshore converter module is determined according to the rated power of the offshore converter module and the power injected by the unit; according to the surplus power, the first threshold voltage Vth1 of the offshore converter module is determined (the first threshold voltage Vth1 is the threshold of the DC voltage of the offshore converter module before the fault).

[0047] Alternatively, as an example, Figure 2 As shown, a first proportionality coefficient of the first threshold voltage Vth1 relative to the first operating voltage U1 is obtained, wherein the first proportionality coefficient=(Vth1-U1) / U1.

[0048] Alternatively, as an example, Figure 2 As shown, according to the first proportional coefficient and the first working voltage U1, the first adjustment voltage of the AC side of the offshore converter module is determined. Further, the first proportional coefficient and the first working voltage U1 are multiplied to obtain a first intermediate variable, wherein the first intermediate variable = the first proportional coefficient * U1. The first working voltage and the first intermediate variable are summed to obtain the first adjustment voltage of the offshore converter module, wherein the first adjustment voltage = the first intermediate variable + U1.

[0049] It should be noted that the amplitude of the first adjustment voltage may also be represented by a first proportionality coefficient and a reference amplitude V1_ref, wherein the amplitude of the first adjustment voltage=V1_ref+first proportionality coefficient*V1_ref.

[0050] S102: Based on the first adjustment voltage, adjust the working mode of each unit in the offshore wind farm to obtain a threshold voltage of the unit.

[0051] In a feasible implementation, when a fault ride-through condition occurs, the voltage measured by the offshore converter module increases, and the voltage amplitude also increases in response. When the voltage amplitude of the offshore wind farm unit detected is ≥ its threshold voltage (the threshold voltage is the voltage threshold of the unit after the fault), the wind turbine unit can be switched to the voltage source working mode, wherein the voltage source working mode controls the voltage amplitude and phase of the unit, and the unit establishes the grid-connected transmission voltage by simulating the operating characteristics of the synchronous generator without relying on the phase-locked loop for synchronization. For example, the deviation between the measured value of the unit voltage and the reference value of the voltage can be proportionally integrated to obtain the power demand of the unit; the grid-side power of the unit is obtained according to the positive sequence component of the bus voltage, the positive sequence component of the filter inductor current and the power feedback coefficient, and then the virtual internal potential phase is determined, and the d-axis component and q-axis component of the modulation voltage are determined accordingly.

[0052] Optionally, as an example, based on the first adjustment voltage, the phase angles of each unit in the offshore wind farm are synchronized (the synchronization operation is to avoid unit power fluctuations caused by phase jumps, so that the phase angle of the unit after the fault remains consistent with the phase angle of the unit before the fault); based on the synchronization operation, the threshold voltage of the unit is obtained, wherein the threshold voltage includes the d-axis component and the q-axis component of the modulation voltage.

[0053] S103, acquiring a first reference value of the active power of the unit according to a fitting operation of the first power and the threshold voltage.

[0054] In a feasible implementation, as an example, a second proportionality coefficient of the threshold voltage relative to the rated voltage of the unit is obtained, wherein the rated voltage is the operating voltage of the unit when no fault ride-through condition occurs, and the second proportionality coefficient = (threshold voltage - rated voltage of the unit) / (regulation coefficient * rated voltage of the unit). It should be noted that the regulation coefficient is set according to actual needs, and usually, the same regulation coefficient is set for each unit in the wind farm.

[0055] Optionally, as an example, the first power and the second proportional coefficient are multiplied to obtain a second intermediate variable, wherein the first power = output power P1 - first adjusted power; the second proportional coefficient = (threshold voltage - unit rated voltage) / (adjustment coefficient * unit rated voltage); the second intermediate variable = first power * second proportional coefficient.

[0056] Optionally, as an example, according to the fitting operation of the power injected by the unit into the offshore converter module and the second intermediate variable, a first reference value of the unit active power is obtained. Further, a differential operation is performed on the power injected by the unit into the offshore converter module and the second intermediate variable to obtain a third intermediate variable, wherein the third intermediate variable = the power injected by the unit - the second intermediate variable. The maximum value between the third intermediate variable and the first power is obtained, and the maximum value is determined as the first reference value of the unit active power, wherein the first reference value = MAX (first power, third intermediate variable).

[0057] It should be noted that, in order to ensure the effectiveness of the fault ride-through control of the offshore wind power system, a second adjustment voltage on the AC side of the offshore converter module can be set based on the first adjustment voltage of the offshore converter module. Accordingly, a second threshold voltage Vth2 on the DC side of the offshore converter module is obtained, wherein the second threshold voltage Vth2>the first threshold voltage Vth1.

[0058] When the voltage on the DC side of the offshore converter module is ≥ the second threshold voltage Vth2, the offshore wind turbine can be triggered to generate reactive power, which can supplement the active power and thus assist in suppressing the output voltage of each unit in the offshore wind farm. Further, based on the second threshold voltage Vth2, the corresponding second adjustment voltage is obtained, wherein the amplitude of the second adjustment voltage is greater than the amplitude of the first adjustment voltage. Furthermore, based on the first adjustment voltage and the second adjustment voltage, the fault at the receiving end is eliminated.

[0059] S104: Based on the first reference value, suppress the rising speed and amplitude of the output voltage of each unit in the offshore wind farm.

[0060] In a feasible implementation, a differential operation is performed on the surplus power transmitted to the offshore converter module and the first reference value to obtain the reactive power of the offshore wind power transmission system; based on the reactive power, the rising speed and amplitude of the output voltage of each unit in the offshore wind farm are suppressed.

[0061] Figure 3 This is a schematic diagram of the joint fault ride-through process of the flexible DC power station and the unit provided in the embodiment of the present application. Figure 3As shown, under normal operating conditions, the offshore converter module operates at a first operating voltage; when a fault occurs at the receiving end, the first adjustment voltage on the AC side of the offshore converter module and the second adjustment voltage on the AC side are determined; based on the first adjustment voltage and the second adjustment voltage, the operating mode of each unit in the offshore wind farm is adjusted. As an example, the wind turbine unit can be switched to a voltage source operating mode; by fitting the first power of the fault ride-through condition of each unit in the offshore wind farm and the threshold voltage of the unit, a first reference value of the active power of the unit is obtained; based on the first reference value, the rising speed and amplitude of the output voltage of each unit in the offshore wind farm are suppressed.

[0062] When the fault at the receiving end is eliminated, the voltage of the offshore converter module and the voltage of the land converter module begin to decrease. Due to the existence of voltage fluctuations, when the voltage drops below the first operating voltage, the wind turbine can still be switched to the voltage source operating mode to adjust the output voltage of each unit in the offshore wind farm until it returns to normal operating conditions.

[0063] In summary, by following the fault ride-through condition, the first power of each unit in the offshore wind farm for the fault ride-through condition and the first adjustment voltage on the AC side of the offshore converter module are obtained; the working mode of each unit in the offshore wind farm is adjusted according to the first adjustment voltage to obtain the threshold voltage of the unit; the first reference value of the unit's active power is obtained by fitting the first power and the threshold voltage, and the rising speed and amplitude of the output voltage of each unit in the offshore wind farm are suppressed based on the first reference value. There is no need for the offshore converter module and the land converter module to communicate with the unit, and the coordinated fault ride-through of the offshore wind turbine and the receiving end is realized when the transmission end fails, which greatly improves the stability of offshore wind power transmission.

[0064] Figure 4 This is a schematic diagram of the structure of an offshore wind power system fault ride-through control system provided in an embodiment of the present application. Figure 4 As shown, the offshore wind power system fault ride-through control system 400 is suitable for Figure 2 The offshore wind power transmission system shown in the figure includes: at least one unit, an offshore converter module, an electric energy transmission module, a land converter module and a land power grid, wherein the offshore converter module is connected to the unit; the electric energy transmission module is connected to the offshore converter module; the land converter module is connected to the electric energy transmission module; the land power grid is connected to the land converter module, and the offshore wind power system fault ride-through control system 400 includes:

[0065] A first acquisition module 401, the first acquisition module 401 acquires, based on the fault ride-through condition, a first power of each unit in the offshore wind farm under the fault ride-through condition and a first adjusted voltage on the AC side of the offshore converter module;

[0066] A second acquisition module 402, the second acquisition module 402 adjusts the working mode of each unit in the offshore wind farm based on the first adjustment voltage to obtain a threshold voltage of the unit;

[0067] A third acquisition module 403, the third acquisition module 403 acquires a first reference value of the active power of the unit according to a fitting operation of the first power and the threshold voltage;

[0068] The regulating module 404 suppresses the rising speed and amplitude of the output voltage of each unit in the offshore wind farm based on the first reference value.

[0069] For further description of the offshore wind power system fault ride-through control system 400, reference may be made to the relevant contents in the above embodiments, which will not be repeated here.

[0070] Figure 5 The present invention is a schematic diagram of the structure of an electronic device provided according to an embodiment of the present application. Figure 5 The electronic device shown is merely an example and should not bring any limitation to the functions and scope of use of the embodiments of the present application.

[0071] like Figure 5 As shown, the electronic device 500 includes a processor 501, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 502 or a program loaded from a memory 506 to a random access memory (RAM) 503. In the RAM 503, various programs and data required for the operation of the electronic device 500 are also stored. The processor 501, the ROM 502, and the RAM 503 are connected to each other via a bus 504. An input / output (I / O) interface 505 is also connected to the bus 504.

[0072] The following components are connected to the I / O interface 505: a memory 506 including a hard disk, etc.; and a communication part 507 including a network interface card such as a LAN (Local Area Network) card, a modem, etc., and the communication part 507 performs communication processing via a network such as the Internet; a drive 508 is also connected to the I / O interface 505 as needed.

[0073] In particular, according to an embodiment of the present application, the process described above with reference to the flowchart can be implemented as a computer software program. For example, an embodiment of the present application includes a computer program carried on a computer-readable medium, and the computer program includes a program code for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from the network through the communication part 507. When the computer program is executed by the processor 501, the above-mentioned functions defined in the method of the present application are executed.

[0074] In an exemplary embodiment, a storage medium including instructions is also provided, such as a memory including instructions, and the instructions can be executed by the processor 501 of the electronic device 500 to complete the above method. Optionally, the storage medium can be a non-transitory computer-readable storage medium, for example, the non-transitory computer-readable storage medium can be a ROM, a random access memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, etc.

[0075] In the present application, a computer-readable storage medium may be any tangible medium containing or storing a program that may be used by or in combination with an instruction execution system, apparatus, or device. In the present application, a computer-readable signal medium may include a data signal propagated in a baseband or as part of a carrier wave, which carries a computer-readable program code. Such propagated data signals may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. A computer-readable signal medium may also be any computer-readable medium other than a computer-readable storage medium, which may send, propagate, or transmit a program for use by or in combination with an instruction execution system, apparatus, or device. The program code contained on the computer-readable medium may be transmitted using any suitable medium, including but not limited to: wireless, wire, optical cable, RF, etc., or any suitable combination of the above.

[0076] Figure 6 It is a schematic diagram of the structure of another electronic device provided according to an embodiment of the present application. Figure 6 The electronic device shown is only an example and should not limit the functions and scope of use of the embodiments of the present application. Figure 6 As shown, the electronic device 600 includes a processor 601 and a memory 602. The memory 602 is used to store program codes, and the processor 601 is connected to the memory 602 to read the program codes from the memory 602 to implement the offshore wind power system fault ride-through control method in the above embodiment.

[0077] Optionally, the number of processors 601 may be one or more.

[0078] Optionally, the electronic device may further include an interface 603, and the number of the interface 603 may be multiple. The interface 603 may be connected to an application program and may receive data from an external device such as a sensor.

[0079] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not disclosed in this application. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the following claims.

[0080] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A fault ride-through control method for an offshore wind power system, characterized in that: Applicable to an offshore wind power transmission system, the offshore wind power transmission system comprises: at least one unit, an offshore converter module, an electric energy transmission module, a land converter module and a land power grid, wherein the offshore converter module is connected to the unit; the electric energy transmission module is connected to the offshore converter module; the land converter module is connected to the electric energy transmission module; the land power grid is connected to the land converter module; the offshore wind power system fault ride-through control method comprises: Based on the fault ride-through condition, obtaining a first power of each unit in the offshore wind farm for the fault ride-through condition and a first adjusted voltage on the AC side of the offshore converter module; Based on the first adjustment voltage, adjusting the working mode of each unit in the offshore wind farm to obtain the threshold voltage of the unit; Acquire a first reference value of the active power of the unit according to a fitting operation of the first power and the threshold voltage; Based on the first reference value, the rising speed and amplitude of the output voltage of each unit in the offshore wind farm are suppressed.

2. The method according to claim 1, characterized in that The obtaining, based on the fault ride-through condition, the first power of each unit in the offshore wind farm under the fault ride-through condition comprises: Monitor the real-time operating status of each unit in the offshore wind farm, and obtain the output power, equivalent inertia constant, rotor speed and speed time constant of each unit; Based on a fault ride-through condition, fitting the equivalent inertia constant, the rotor speed and the speed time constant to obtain a first adjusted power of each unit; A differential operation is performed on the output power and the first adjusted power to obtain a first power of each unit in the offshore wind farm for a fault ride-through condition.

3. The method according to claim 1, characterized in that The obtaining, based on the fault ride-through condition, a first adjusted voltage on the AC side of the offshore converter module comprises: Obtaining a first working voltage on the AC side when the offshore converter module does not fail through a working condition; Determining a first threshold voltage on a DC side of an offshore converter module based on a fault ride-through condition; Obtaining a first proportionality coefficient of the first threshold voltage relative to the first operating voltage; A first adjustment voltage on the AC side of the offshore converter module is determined according to the first proportional coefficient and the first operating voltage.

4. The method according to claim 3, characterized in that The determining, based on the fault ride-through condition, a first threshold voltage on the DC side of the offshore converter module comprises: In response to a fault ride-through condition, determining a surplus power transmitted to the offshore converter module according to the rated power of the offshore converter module and the power injected into the offshore converter module by the unit; A first threshold voltage on the DC side of the offshore converter module is determined according to the surplus power.

5. The method according to claim 3, characterized in that: The step of determining a first adjustment voltage on the AC side of the offshore converter module according to the first proportional coefficient and the first operating voltage includes: Performing a product operation on the first proportional coefficient and the first operating voltage to obtain a first intermediate variable; A sum operation is performed on the first working voltage and the first intermediate variable to obtain a first adjusted voltage of the offshore converter module.

6. The method according to claim 1, characterized in that The step of adjusting the working mode of each unit in the offshore wind farm based on the first adjustment voltage to obtain the threshold voltage of the unit includes: Based on the first adjusted voltage, synchronizing the phase angles of the units in the offshore wind farm; Based on the synchronous operation, a threshold voltage of the generator set is obtained.

7. The method according to claim 1, characterized in that The step of obtaining a first reference value of the active power of the unit according to the fitting operation of the first power and the threshold voltage includes: Obtaining a second proportionality coefficient of the threshold voltage relative to the rated voltage of the unit; Performing a product operation on the first power and the second proportional coefficient to obtain a second intermediate variable; According to the fitting operation of the power injected into the offshore converter module by the unit and the second intermediate variable, a first reference value of the active power of the unit is obtained.

8. The method according to claim 7, characterized in that The step of obtaining a first reference value of the active power of the unit according to the fitting operation of the power injected into the offshore converter module by the unit and the second intermediate variable comprises: Performing a differential operation on the power injected into the offshore converter module by the unit and the second intermediate variable to obtain a third intermediate variable; A maximum value between the third intermediate variable and the first power is obtained, and the maximum value is determined as a first reference value of the active power of the unit.

9. The method according to claim 1, characterized in that: The step of suppressing the rising speed and amplitude of the output voltage of each unit in the offshore wind farm based on the first reference value includes: Performing a differential operation on the surplus power transmitted to the offshore converter module and the first reference value to obtain the reactive power of the offshore wind power transmission system; According to the reactive power, the rising speed and amplitude of the output voltage of each unit in the offshore wind farm are suppressed.

10. An offshore wind power system fault ride-through control system, characterized in that: Applicable to an offshore wind power transmission system, the offshore wind power transmission system comprises: at least one unit, an offshore converter module, an electric energy transmission module, a land converter module and a land power grid, wherein the offshore converter module is connected to the unit; the electric energy transmission module is connected to the offshore converter module; the land converter module is connected to the electric energy transmission module; the land power grid is connected to the land converter module; the offshore wind power system fault ride-through control system comprises: A first acquisition module, wherein the first acquisition module acquires, based on the fault ride-through condition, a first power of each unit in the offshore wind farm under the fault ride-through condition and a first adjusted voltage on the AC side of the offshore converter module; a second acquisition module, wherein the second acquisition module adjusts the working mode of each unit in the offshore wind farm based on the first adjustment voltage to obtain a threshold voltage of the unit; a third acquisition module, wherein the third acquisition module acquires a first reference value of the active power of the unit according to a fitting operation of the first power and the threshold voltage; A regulating module, wherein the regulating module suppresses a rising speed and amplitude of an output voltage of each unit in the offshore wind farm based on the first reference value.

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